FAIR VALUE OF FINANCIAL ASSETS AND LIABILITIES (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Assets and liabilities measured at fair value
Available for sale securities:	$ 1,408,124	$ 1,407,999
States and political subdivisions debt securities
Assets and liabilities measured at fair value
Available for sale securities:	185,126	179,357
Corporate bonds and debentures
Assets and liabilities measured at fair value
Available for sale securities:	158,291	158,095
U.S. Government sponsored entities mortgage-backed securities
Assets and liabilities measured at fair value
Available for sale securities:	899,066	927,626
Non-agency collateralized mortgage obligations
Assets and liabilities measured at fair value
Available for sale securities:	164,859	142,046
Other
Assets and liabilities measured at fair value
Available for sale securities:	782	875
Recurring basis \| Fair Value
Assets and liabilities measured at fair value
Total	1,408,164	1,408,278
Recurring basis \| Fair Value \| Interest rate contracts
Assets and liabilities measured at fair value
Derivatives:	40	279
Recurring basis \| Fair Value \| States and political subdivisions debt securities
Assets and liabilities measured at fair value
Available for sale securities:	185,126	179,357
Recurring basis \| Fair Value \| Corporate bonds and debentures
Assets and liabilities measured at fair value
Available for sale securities:	158,291	158,095
Recurring basis \| Fair Value \| U.S. Government sponsored entities mortgage-backed securities
Assets and liabilities measured at fair value
Available for sale securities:	899,066	927,626
Recurring basis \| Fair Value \| Non-agency collateralized mortgage obligations
Assets and liabilities measured at fair value
Available for sale securities:	164,859	142,046
Recurring basis \| Fair Value \| Other
Assets and liabilities measured at fair value
Available for sale securities:	782	875
Recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets and liabilities measured at fair value
Total	782	875
Recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Other
Assets and liabilities measured at fair value
Available for sale securities:	782	875
Recurring basis \| Significant Other Observable Inputs (Level 2)
Assets and liabilities measured at fair value
Total	1,395,594	1,396,885
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Interest rate contracts
Assets and liabilities measured at fair value
Derivatives:	40	279
Recurring basis \| Significant Other Observable Inputs (Level 2) \| States and political subdivisions debt securities
Assets and liabilities measured at fair value
Available for sale securities:	173,338	168,839
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Corporate bonds and debentures
Assets and liabilities measured at fair value
Available for sale securities:	158,291	158,095
Recurring basis \| Significant Other Observable Inputs (Level 2) \| U.S. Government sponsored entities mortgage-backed securities
Assets and liabilities measured at fair value
Available for sale securities:	899,066	927,626
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Non-agency collateralized mortgage obligations
Assets and liabilities measured at fair value
Available for sale securities:	164,859	142,046
Recurring basis \| Significant Unobservable Inputs (Level 3)
Assets and liabilities measured at fair value
Total	11,788	10,518
Recurring basis \| Significant Unobservable Inputs (Level 3) \| States and political subdivisions debt securities
Assets and liabilities measured at fair value
Available for sale securities:	$ 11,788	$ 10,518